From 1a852f7c1e27eef563cf0577c2604baec1be5512 Mon Sep 17 00:00:00 2001 From: Alvaro Herrera Date: Sat, 6 Oct 2018 19:17:46 -0300 Subject: Fix event triggers for partitioned tables MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Index DDL cascading on partitioned tables introduced a way for ALTER TABLE to be called reentrantly. This caused an an important deficiency in event trigger support to be exposed: on exiting the reentrant call, the alter table state object was clobbered, causing a crash when the outer alter table tries to finalize its processing. Fix the crash by creating a stack of event trigger state objects. There are still ways to cause things to misbehave (and probably other crashers) with more elaborate tricks, but at least it now doesn't crash in the obvious scenario. Backpatch to 9.5, where DDL deparsing of event triggers was introduced. Reported-by: Marco Slot Authors: Michaël Paquier, Álvaro Herrera Discussion: https://postgr.es/m/CANNhMLCpi+HQ7M36uPfGbJZEQLyTy7XvX=5EFkpR-b1bo0uJew@mail.gmail.com --- src/backend/commands/event_trigger.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) (limited to 'src/backend/commands/event_trigger.c') diff --git a/src/backend/commands/event_trigger.c b/src/backend/commands/event_trigger.c index eecc85d14e5..2c1dc47541c 100644 --- a/src/backend/commands/event_trigger.c +++ b/src/backend/commands/event_trigger.c @@ -1696,11 +1696,6 @@ EventTriggerCollectSimpleCommand(ObjectAddress address, * Note we don't collect the command immediately; instead we keep it in * currentCommand, and only when we're done processing the subcommands we will * add it to the command list. - * - * XXX -- this API isn't considering the possibility of an ALTER TABLE command - * being called reentrantly by an event trigger function. Do we need stackable - * commands at this level? Perhaps at least we should detect the condition and - * raise an error. */ void EventTriggerAlterTableStart(Node *parsetree) @@ -1725,6 +1720,7 @@ EventTriggerAlterTableStart(Node *parsetree) command->d.alterTable.subcmds = NIL; command->parsetree = copyObject(parsetree); + command->parent = currentEventTriggerState->currentCommand; currentEventTriggerState->currentCommand = command; MemoryContextSwitchTo(oldcxt); @@ -1765,6 +1761,7 @@ EventTriggerCollectAlterTableSubcmd(Node *subcmd, ObjectAddress address) return; Assert(IsA(subcmd, AlterTableCmd)); + Assert(OidIsValid(currentEventTriggerState->currentCommand)); Assert(OidIsValid(currentEventTriggerState->currentCommand->d.alterTable.objectId)); oldcxt = MemoryContextSwitchTo(currentEventTriggerState->cxt); @@ -1790,11 +1787,15 @@ EventTriggerCollectAlterTableSubcmd(Node *subcmd, ObjectAddress address) void EventTriggerAlterTableEnd(void) { + CollectedCommand *parent; + /* ignore if event trigger context not set, or collection disabled */ if (!currentEventTriggerState || currentEventTriggerState->commandCollectionInhibited) return; + parent = currentEventTriggerState->currentCommand->parent; + /* If no subcommands, don't collect */ if (list_length(currentEventTriggerState->currentCommand->d.alterTable.subcmds) != 0) { @@ -1805,7 +1806,7 @@ EventTriggerAlterTableEnd(void) else pfree(currentEventTriggerState->currentCommand); - currentEventTriggerState->currentCommand = NULL; + currentEventTriggerState->currentCommand = parent; } /* -- cgit v1.2.3